1. Field of the Invention
This invention relates to laundry detergent compositions, and, more particularly, to such compositions containing a polymer which is a water soluble poly(vinylpyridine) betaine containing a quaternary nitrogen and a carboxylic acid group, which polymers have effective dye complexing properties therein.
2. Description of the Prior Art
Dye complexing polymers have been used in laundry detergent and fabric softener compositions. In such application, during washing a mixture of colored and white fabrics, some of the dyes may bleed out of a colored fabric under washing conditions. The degree of bleeding is influenced by the structure of the dye, the type of cloth and the pH, temperature and mechanical efficiency of the agitation process. The bled dye in the wash liquor can be totally innocuous and get washed off in the wash liquor. However, in reality, this fugitive dye has a tendency to redeposit either onto the same fabric or onto another fabric leading to patches and an ugly appearance of the washed material. This redeposition of the bled dye can be inhibited in several ways. One method is to introduce compounds which can complex with the fugitive dye and get washed off thus preventing redeposition.
Polyvinylpyrrolidone (PVP), by virtue of its dye complexation ability, has been used to inhibit dye deposition during washing of colored fabrics under laundry conditions. The performance of PVP as a DTI, however, is adversely affected by the presence of anionic surfactants in the washing process.
Other polymers which have been used as DTIs in laundry detergent compositions include polyvinylpyridine N-oxide (PVPNO); polyvinylimidazole (PVI) and copolymers of polyvinylpyridine and polyvinylimidazole (PVP-PVI).
U.S. Pat. Nos. 5,776,879; 5,929,175; 5,869,442; 5,863,880, assigned to the same assignee as herein are related to this invention.
The other prior art in this field is represented by the following patents and publications:
Accordingly, it is an object of this invention to provide new and improved laundry detergent compositions containing effective water soluble dye complexing polymers.
A feature of the invention is the provision of a water soluble poly(vinylpyridine) betaine containing a quaternary nitrogen and a carboxylic acid group as the dye transfer complexing polymer in laundry detergent compositions.
Another feature of the invention is the provision of laundry detergent compositions containing such new and improved water soluble poly(vinylpyridine) polymers, which exhibit color stability during storage, and particularly effective dye complexing properties during the washing process even in the presence of anionic surfactants.
What is described herein is a laundry detergent composition containing a water soluble poly(vinylpyridine betaine) polymer which contains a quaternary nitrogen and a carboxylic acid group. The polymer has the formula: 
where m is indicative of the degree of polymerization,
X is an anion,
R1, R2, R3 and R4 are independently hydrogen, alkyl or aryl, and
n is 1-6,
and quats and copolymers thereof.
Preferred embodiments of the invention are polymers in which X is hydroxyl; R1, R2, R3 and R4 are hydrogen; n is 1 or 2; and the polymer is 25-100% quaternized; most preferably 75-100%.
A suitable polymer has a weight average molecular weight of about 5,000 to 1,000,000; preferably 20,000 to 200,000, where m is about 30-5000, preferably 100-1000.
Water soluble copolymers of the defined polymer above with polymerizable comonomers, such as vinyl pyrrolidone, vinyl imidazole, acrylamide and vinyl caprolactam also are useful herein.
The polymers of the invention have effective dye complexing properties for use in laundry detergent compositions which include at least 1% by weight of an anionic, cationic or non-ionic surfactant or mixtures thereof.
The dye transfer inhibition polymers of the invention wherein n=2-6 and X is OH are made by reacting a poly(vinylpyridine) with an xcex1,xcex2-unsaturated carboxylic acid by Michael addition. Suitable xcex1,xcex2-unsaturated acids in this reaction include crotonic acid, itaconic acid, maleic acid, fumaric acid, acrylic acid, methacrylic acid and the like. Crotonic acid is preferred. In aqueous medium the betaine anion is hydroxyl.
A preferred polymer herein is poly(4-vinylpyridine) carboxyethyl betaine hydroxide having the formula: 
which is made by reacting poly(4-vinylpyridine) with crotonic acid to form the betaine carboxylate followed by addition of water to form the desired betaine carboxylic acid.
Polymers of the invention wherein n=1-6 and X is a halide are made by reacting poly(4-vinylpyridine) with a halocarboxylic acid such as 2-chloroacetic acid, 2 or 3-chloropropionic acid, and the like.
The invention will now be described in more detail with reference to the following examples.